/*
 * jdmaster.c
 *
 * Copyright (C) 1991-1995, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains master control logic for the JPEG decompressor.
 * These routines are concerned with selecting the modules to be executed
 * and with determining the number of passes and the work to be done in each
 * pass.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"


/* Private state */

typedef struct
{
	struct jpeg_decomp_master pub;	/* public fields */

	int             pass_number;	/* # of passes completed */

	boolean         using_merged_upsample;	/* TRUE if using merged upsample/cconvert */

	/* Saved references to initialized quantizer modules,
	 * in case we need to switch modes.
	 */
	struct jpeg_color_quantizer *quantizer_1pass;
	struct jpeg_color_quantizer *quantizer_2pass;
} my_decomp_master;

typedef my_decomp_master *my_master_ptr;


/*
 * Determine whether merged upsample/color conversion should be used.
 * CRUCIAL: this must match the actual capabilities of jdmerge.c!
 */

LOCAL           boolean use_merged_upsample(j_decompress_ptr cinfo)
{
#ifdef UPSAMPLE_MERGING_SUPPORTED
	/* Merging is the equivalent of plain box-filter upsampling */
	if(cinfo->do_fancy_upsampling || cinfo->CCIR601_sampling)
		return FALSE;
	/* jdmerge.c only supports YCC=>RGB color conversion */
	if(cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 ||
	   cinfo->out_color_space != JCS_RGB || cinfo->out_color_components != RGB_PIXELSIZE)
		return FALSE;
	/* and it only handles 2h1v or 2h2v sampling ratios */
	if(cinfo->comp_info[0].h_samp_factor != 2 ||
	   cinfo->comp_info[1].h_samp_factor != 1 ||
	   cinfo->comp_info[2].h_samp_factor != 1 ||
	   cinfo->comp_info[0].v_samp_factor > 2 || cinfo->comp_info[1].v_samp_factor != 1 || cinfo->comp_info[2].v_samp_factor != 1)
		return FALSE;
	/* furthermore, it doesn't work if we've scaled the IDCTs differently */
	if(cinfo->comp_info[0].DCT_scaled_size != cinfo->min_DCT_scaled_size ||
	   cinfo->comp_info[1].DCT_scaled_size != cinfo->min_DCT_scaled_size ||
	   cinfo->comp_info[2].DCT_scaled_size != cinfo->min_DCT_scaled_size)
		return FALSE;
	/* ??? also need to test for upsample-time rescaling, when & if supported */
	return TRUE;				/* by golly, it'll work... */
#else
	return FALSE;
#endif
}


/*
 * Compute output image dimensions and related values.
 * NOTE: this is exported for possible use by application.
 * Hence it mustn't do anything that can't be done twice.
 * Also note that it may be called before the master module is initialized!
 */

GLOBAL void jpeg_calc_output_dimensions(j_decompress_ptr cinfo)
/* Do computations that are needed before master selection phase */
{
#if 0							// JDC: commented out to remove warning
	int             ci;
	jpeg_component_info *compptr;
#endif

	/* Prevent application from calling me at wrong times */
	if(cinfo->global_state != DSTATE_READY)
		ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

#ifdef IDCT_SCALING_SUPPORTED

	/* Compute actual output image dimensions and DCT scaling choices. */
	if(cinfo->scale_num * 8 <= cinfo->scale_denom)
	{
		/* Provide 1/8 scaling */
		cinfo->output_width = (JDIMENSION) jdiv_round_up((long)cinfo->image_width, 8L);
		cinfo->output_height = (JDIMENSION) jdiv_round_up((long)cinfo->image_height, 8L);
		cinfo->min_DCT_scaled_size = 1;
	}
	else if(cinfo->scale_num * 4 <= cinfo->scale_denom)
	{
		/* Provide 1/4 scaling */
		cinfo->output_width = (JDIMENSION) jdiv_round_up((long)cinfo->image_width, 4L);
		cinfo->output_height = (JDIMENSION) jdiv_round_up((long)cinfo->image_height, 4L);
		cinfo->min_DCT_scaled_size = 2;
	}
	else if(cinfo->scale_num * 2 <= cinfo->scale_denom)
	{
		/* Provide 1/2 scaling */
		cinfo->output_width = (JDIMENSION) jdiv_round_up((long)cinfo->image_width, 2L);
		cinfo->output_height = (JDIMENSION) jdiv_round_up((long)cinfo->image_height, 2L);
		cinfo->min_DCT_scaled_size = 4;
	}
	else
	{
		/* Provide 1/1 scaling */
		cinfo->output_width = cinfo->image_width;
		cinfo->output_height = cinfo->image_height;
		cinfo->min_DCT_scaled_size = DCTSIZE;
	}
	/* In selecting the actual DCT scaling for each component, we try to
	 * scale up the chroma components via IDCT scaling rather than upsampling.
	 * This saves time if the upsampler gets to use 1:1 scaling.
	 * Note this code assumes that the supported DCT scalings are powers of 2.
	 */
	for(ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; ci++, compptr++)
	{
		int             ssize = cinfo->min_DCT_scaled_size;

		while(ssize < DCTSIZE &&
			  (compptr->h_samp_factor * ssize * 2 <=
			   cinfo->max_h_samp_factor * cinfo->min_DCT_scaled_size) &&
			  (compptr->v_samp_factor * ssize * 2 <= cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size))
		{
			ssize = ssize * 2;
		}
		compptr->DCT_scaled_size = ssize;
	}

	/* Recompute downsampled dimensions of components;
	 * application needs to know these if using raw downsampled data.
	 */
	for(ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components; ci++, compptr++)
	{
		/* Size in samples, after IDCT scaling */
		compptr->downsampled_width = (JDIMENSION)
			jdiv_round_up((long)cinfo->image_width *
						  (long)(compptr->h_samp_factor * compptr->DCT_scaled_size), (long)(cinfo->max_h_samp_factor * DCTSIZE));
		compptr->downsampled_height = (JDIMENSION)
			jdiv_round_up((long)cinfo->image_height *
						  (long)(compptr->v_samp_factor * compptr->DCT_scaled_size), (long)(cinfo->max_v_samp_factor * DCTSIZE));
	}

#else							/* !IDCT_SCALING_SUPPORTED */

	/* Hardwire it to "no scaling" */
	cinfo->output_width = cinfo->image_width;
	cinfo->output_height = cinfo->image_height;
	/* jdinput.c has already initialized DCT_scaled_size to DCTSIZE,
	 * and has computed unscaled downsampled_width and downsampled_height.
	 */

#endif							/* IDCT_SCALING_SUPPORTED */

	/* Report number of components in selected colorspace. */
	/* Probably this should be in the color conversion module... */
	switch (cinfo->out_color_space)
	{
		case JCS_GRAYSCALE:
			cinfo->out_color_components = 1;
			break;
		case JCS_RGB:
#if RGB_PIXELSIZE != 3
			cinfo->out_color_components = RGB_PIXELSIZE;
			break;
#endif							/* else share code with YCbCr */
		case JCS_YCbCr:
			cinfo->out_color_components = 3;
			break;
		case JCS_CMYK:
		case JCS_YCCK:
			cinfo->out_color_components = 4;
			break;
		default:				/* else must be same colorspace as in file */
			cinfo->out_color_components = cinfo->num_components;
			break;
	}
	cinfo->output_components = (cinfo->quantize_colors ? 1 : cinfo->out_color_components);

	/* See if upsampler will want to emit more than one row at a time */
	if(use_merged_upsample(cinfo))
		cinfo->rec_outbuf_height = cinfo->max_v_samp_factor;
	else
		cinfo->rec_outbuf_height = 1;
}


/*
 * Several decompression processes need to range-limit values to the range
 * 0..MAXJSAMPLE; the input value may fall somewhat outside this range
 * due to noise introduced by quantization, roundoff error, etc.  These
 * processes are inner loops and need to be as fast as possible.  On most
 * machines, particularly CPUs with pipelines or instruction prefetch,
 * a (subscript-check-less) C table lookup
 *		x = sample_range_limit[x];
 * is faster than explicit tests
 *		if (x < 0)  x = 0;
 *		else if (x > MAXJSAMPLE)  x = MAXJSAMPLE;
 * These processes all use a common table prepared by the routine below.
 *
 * For most steps we can mathematically guarantee that the initial value
 * of x is within MAXJSAMPLE+1 of the legal range, so a table running from
 * -(MAXJSAMPLE+1) to 2*MAXJSAMPLE+1 is sufficient.  But for the initial
 * limiting step (just after the IDCT), a wildly out-of-range value is 
 * possible if the input data is corrupt.  To avoid any chance of indexing
 * off the end of memory and getting a bad-pointer trap, we perform the
 * post-IDCT limiting thus:
 *		x = range_limit[x & MASK];
 * where MASK is 2 bits wider than legal sample data, ie 10 bits for 8-bit
 * samples.  Under normal circumstances this is more than enough range and
 * a correct output will be generated; with bogus input data the mask will
 * cause wraparound, and we will safely generate a bogus-but-in-range output.
 * For the post-IDCT step, we want to convert the data from signed to unsigned
 * representation by adding CENTERJSAMPLE at the same time that we limit it.
 * So the post-IDCT limiting table ends up looking like this:
 *   CENTERJSAMPLE,CENTERJSAMPLE+1,...,MAXJSAMPLE,
 *   MAXJSAMPLE (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
 *   0          (repeat 2*(MAXJSAMPLE+1)-CENTERJSAMPLE times),
 *   0,1,...,CENTERJSAMPLE-1
 * Negative inputs select values from the upper half of the table after
 * masking.
 *
 * We can save some space by overlapping the start of the post-IDCT table
 * with the simpler range limiting table.  The post-IDCT table begins at
 * sample_range_limit + CENTERJSAMPLE.
 *
 * Note that the table is allocated in near data space on PCs; it's small
 * enough and used often enough to justify this.
 */

LOCAL void prepare_range_limit_table(j_decompress_ptr cinfo)
/* Allocate and fill in the sample_range_limit table */
{
	JSAMPLE        *table;
	int             i;

	table = (JSAMPLE *)
		(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, (5 * (MAXJSAMPLE + 1) + CENTERJSAMPLE) * SIZEOF(JSAMPLE));
	table += (MAXJSAMPLE + 1);	/* allow negative subscripts of simple table */
	cinfo->sample_range_limit = table;
	/* First segment of "simple" table: limit[x] = 0 for x < 0 */
	MEMZERO(table - (MAXJSAMPLE + 1), (MAXJSAMPLE + 1) * SIZEOF(JSAMPLE));
	/* Main part of "simple" table: limit[x] = x */
	for(i = 0; i <= MAXJSAMPLE; i++)
		table[i] = (JSAMPLE) i;
	table += CENTERJSAMPLE;		/* Point to where post-IDCT table starts */
	/* End of simple table, rest of first half of post-IDCT table */
	for(i = CENTERJSAMPLE; i < 2 * (MAXJSAMPLE + 1); i++)
		table[i] = MAXJSAMPLE;
	/* Second half of post-IDCT table */
	MEMZERO(table + (2 * (MAXJSAMPLE + 1)), (2 * (MAXJSAMPLE + 1) - CENTERJSAMPLE) * SIZEOF(JSAMPLE));
	MEMCOPY(table + (4 * (MAXJSAMPLE + 1) - CENTERJSAMPLE), cinfo->sample_range_limit, CENTERJSAMPLE * SIZEOF(JSAMPLE));
}


/*
 * Master selection of decompression modules.
 * This is done once at jpeg_start_decompress time.  We determine
 * which modules will be used and give them appropriate initialization calls.
 * We also initialize the decompressor input side to begin consuming data.
 *
 * Since jpeg_read_header has finished, we know what is in the SOF
 * and (first) SOS markers.  We also have all the application parameter
 * settings.
 */

LOCAL void master_selection(j_decompress_ptr cinfo)
{
	my_master_ptr   master = (my_master_ptr) cinfo->master;
	boolean         use_c_buffer;
	long            samplesperrow;
	JDIMENSION      jd_samplesperrow;

	/* Initialize dimensions and other stuff */
	jpeg_calc_output_dimensions(cinfo);
	prepare_range_limit_table(cinfo);

	/* Width of an output scanline must be representable as JDIMENSION. */
	samplesperrow = (long)cinfo->output_width * (long)cinfo->out_color_components;
	jd_samplesperrow = (JDIMENSION) samplesperrow;
	if((long)jd_samplesperrow != samplesperrow)
		ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);

	/* Initialize my private state */
	master->pass_number = 0;
	master->using_merged_upsample = use_merged_upsample(cinfo);

	/* Color quantizer selection */
	master->quantizer_1pass = NULL;
	master->quantizer_2pass = NULL;
	/* No mode changes if not using buffered-image mode. */
	if(!cinfo->quantize_colors || !cinfo->buffered_image)
	{
		cinfo->enable_1pass_quant = FALSE;
		cinfo->enable_external_quant = FALSE;
		cinfo->enable_2pass_quant = FALSE;
	}
	if(cinfo->quantize_colors)
	{
		if(cinfo->raw_data_out)
			ERREXIT(cinfo, JERR_NOTIMPL);
		/* 2-pass quantizer only works in 3-component color space. */
		if(cinfo->out_color_components != 3)
		{
			cinfo->enable_1pass_quant = TRUE;
			cinfo->enable_external_quant = FALSE;
			cinfo->enable_2pass_quant = FALSE;
			cinfo->colormap = NULL;
		}
		else if(cinfo->colormap != NULL)
		{
			cinfo->enable_external_quant = TRUE;
		}
		else if(cinfo->two_pass_quantize)
		{
			cinfo->enable_2pass_quant = TRUE;
		}
		else
		{
			cinfo->enable_1pass_quant = TRUE;
		}

		if(cinfo->enable_1pass_quant)
		{
#ifdef QUANT_1PASS_SUPPORTED
			jinit_1pass_quantizer(cinfo);
			master->quantizer_1pass = cinfo->cquantize;
#else
			ERREXIT(cinfo, JERR_NOT_COMPILED);
#endif
		}

		/* We use the 2-pass code to map to external colormaps. */
		if(cinfo->enable_2pass_quant || cinfo->enable_external_quant)
		{
#ifdef QUANT_2PASS_SUPPORTED
			jinit_2pass_quantizer(cinfo);
			master->quantizer_2pass = cinfo->cquantize;
#else
			ERREXIT(cinfo, JERR_NOT_COMPILED);
#endif
		}
		/* If both quantizers are initialized, the 2-pass one is left active;
		 * this is necessary for starting with quantization to an external map.
		 */
	}

	/* Post-processing: in particular, color conversion first */
	if(!cinfo->raw_data_out)
	{
		if(master->using_merged_upsample)
		{
#ifdef UPSAMPLE_MERGING_SUPPORTED
			jinit_merged_upsampler(cinfo);	/* does color conversion too */
#else
			ERREXIT(cinfo, JERR_NOT_COMPILED);
#endif
		}
		else
		{
			jinit_color_deconverter(cinfo);
			jinit_upsampler(cinfo);
		}
		jinit_d_post_controller(cinfo, cinfo->enable_2pass_quant);
	}
	/* Inverse DCT */
	jinit_inverse_dct(cinfo);
	/* Entropy decoding: either Huffman or arithmetic coding. */
	if(cinfo->arith_code)
	{
		ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
	}
	else
	{
		if(cinfo->progressive_mode)
		{
#ifdef D_PROGRESSIVE_SUPPORTED
			jinit_phuff_decoder(cinfo);
#else
			ERREXIT(cinfo, JERR_NOT_COMPILED);
#endif
		}
		else
			jinit_huff_decoder(cinfo);
	}

	/* Initialize principal buffer controllers. */
	use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image;
	jinit_d_coef_controller(cinfo, use_c_buffer);

	if(!cinfo->raw_data_out)
		jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */ );

	/* We can now tell the memory manager to allocate virtual arrays. */
	(*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);

	/* Initialize input side of decompressor to consume first scan. */
	(*cinfo->inputctl->start_input_pass) (cinfo);

#ifdef D_MULTISCAN_FILES_SUPPORTED
	/* If jpeg_start_decompress will read the whole file, initialize
	 * progress monitoring appropriately.  The input step is counted
	 * as one pass.
	 */
	if(cinfo->progress != NULL && !cinfo->buffered_image && cinfo->inputctl->has_multiple_scans)
	{
		int             nscans;

		/* Estimate number of scans to set pass_limit. */
		if(cinfo->progressive_mode)
		{
			/* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
			nscans = 2 + 3 * cinfo->num_components;
		}
		else
		{
			/* For a nonprogressive multiscan file, estimate 1 scan per component. */
			nscans = cinfo->num_components;
		}
		cinfo->progress->pass_counter = 0L;
		cinfo->progress->pass_limit = (long)cinfo->total_iMCU_rows * nscans;
		cinfo->progress->completed_passes = 0;
		cinfo->progress->total_passes = (cinfo->enable_2pass_quant ? 3 : 2);
		/* Count the input pass as done */
		master->pass_number++;
	}
#endif							/* D_MULTISCAN_FILES_SUPPORTED */
}


/*
 * Per-pass setup.
 * This is called at the beginning of each output pass.  We determine which
 * modules will be active during this pass and give them appropriate
 * start_pass calls.  We also set is_dummy_pass to indicate whether this
 * is a "real" output pass or a dummy pass for color quantization.
 * (In the latter case, jdapi.c will crank the pass to completion.)
 */

METHODDEF void prepare_for_output_pass(j_decompress_ptr cinfo)
{
	my_master_ptr   master = (my_master_ptr) cinfo->master;

	if(master->pub.is_dummy_pass)
	{
#ifdef QUANT_2PASS_SUPPORTED
		/* Final pass of 2-pass quantization */
		master->pub.is_dummy_pass = FALSE;
		(*cinfo->cquantize->start_pass) (cinfo, FALSE);
		(*cinfo->post->start_pass) (cinfo, JBUF_CRANK_DEST);
		(*cinfo->main->start_pass) (cinfo, JBUF_CRANK_DEST);
#else
		ERREXIT(cinfo, JERR_NOT_COMPILED);
#endif							/* QUANT_2PASS_SUPPORTED */
	}
	else
	{
		if(cinfo->quantize_colors && cinfo->colormap == NULL)
		{
			/* Select new quantization method */
			if(cinfo->two_pass_quantize && cinfo->enable_2pass_quant)
			{
				cinfo->cquantize = master->quantizer_2pass;
				master->pub.is_dummy_pass = TRUE;
			}
			else if(cinfo->enable_1pass_quant)
			{
				cinfo->cquantize = master->quantizer_1pass;
			}
			else
			{
				ERREXIT(cinfo, JERR_MODE_CHANGE);
			}
		}
		(*cinfo->idct->start_pass) (cinfo);
		(*cinfo->coef->start_output_pass) (cinfo);
		if(!cinfo->raw_data_out)
		{
			if(!master->using_merged_upsample)
				(*cinfo->cconvert->start_pass) (cinfo);
			(*cinfo->upsample->start_pass) (cinfo);
			if(cinfo->quantize_colors)
				(*cinfo->cquantize->start_pass) (cinfo, master->pub.is_dummy_pass);
			(*cinfo->post->start_pass) (cinfo, (master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
			(*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
		}
	}

	/* Set up progress monitor's pass info if present */
	if(cinfo->progress != NULL)
	{
		cinfo->progress->completed_passes = master->pass_number;
		cinfo->progress->total_passes = master->pass_number + (master->pub.is_dummy_pass ? 2 : 1);
		/* In buffered-image mode, we assume one more output pass if EOI not
		 * yet reached, but no more passes if EOI has been reached.
		 */
		if(cinfo->buffered_image && !cinfo->inputctl->eoi_reached)
		{
			cinfo->progress->total_passes += (cinfo->enable_2pass_quant ? 2 : 1);
		}
	}
}


/*
 * Finish up at end of an output pass.
 */

METHODDEF void finish_output_pass(j_decompress_ptr cinfo)
{
	my_master_ptr   master = (my_master_ptr) cinfo->master;

	if(cinfo->quantize_colors)
		(*cinfo->cquantize->finish_pass) (cinfo);
	master->pass_number++;
}


#ifdef D_MULTISCAN_FILES_SUPPORTED

/*
 * Switch to a new external colormap between output passes.
 */

GLOBAL void jpeg_new_colormap(j_decompress_ptr cinfo)
{
	my_master_ptr   master = (my_master_ptr) cinfo->master;

	/* Prevent application from calling me at wrong times */
	if(cinfo->global_state != DSTATE_BUFIMAGE)
		ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

	if(cinfo->quantize_colors && cinfo->enable_external_quant && cinfo->colormap != NULL)
	{
		/* Select 2-pass quantizer for external colormap use */
		cinfo->cquantize = master->quantizer_2pass;
		/* Notify quantizer of colormap change */
		(*cinfo->cquantize->new_color_map) (cinfo);
		master->pub.is_dummy_pass = FALSE;	/* just in case */
	}
	else
		ERREXIT(cinfo, JERR_MODE_CHANGE);
}

#endif							/* D_MULTISCAN_FILES_SUPPORTED */


/*
 * Initialize master decompression control and select active modules.
 * This is performed at the start of jpeg_start_decompress.
 */

GLOBAL void jinit_master_decompress(j_decompress_ptr cinfo)
{
	my_master_ptr   master;

	master = (my_master_ptr) (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, SIZEOF(my_decomp_master));
	cinfo->master = (struct jpeg_decomp_master *)master;
	master->pub.prepare_for_output_pass = prepare_for_output_pass;
	master->pub.finish_output_pass = finish_output_pass;

	master->pub.is_dummy_pass = FALSE;

	master_selection(cinfo);
}
